From left, vehicle operator Cheryl Torgerson, Knox County Sheriff's Sgt. John Palmer and Lt. Kirk Guerette look over the car that Torgerson was driving after she allegedly lost control, struck several cars and a family in this August 2013 file photo.

PORT CLYDE, Maine — The Knox County district attorney said Thursday that he would not prosecute the driver involved in a fatal car crash on the Port Clyde pier last summer because he lacked evidence to prove she was criminally negligent.

On Aug. 11, 2013, a car driven by Cheryl Torgerson, 61, of New York City crashed into several vehicles and a building in the ferry terminal area of Port Clyde, killing 9-year-old Dylan Gold of Cohasset, Mass., and injuring his mother, Allison Gold, 6-year-old brother, Wyatt, and Port Clyde resident Jonathan Coggeshall.

“Were there sufficient evidence to show that Cheryl Torgerson is criminally responsible for Dylan’s death and for severe injuries to Allison Gold and Jonathan Coggeshall, a case would be prosecuted to the fullest extent possible,” Knox County District Attorney Geoffrey Rushlau said in a prepared statement issued Thursday. “At this time, there is not that level of evidence.”

In highlighting evidence from the case that had yet to be shared with the public, Rushlau stated that investigators were able to analyze data from the airbag module in Torgerson’s 2007 Infiniti G35 from seven seconds before the airbag deployed to six seconds after. The module recorded vehicle speed, engine RPM, throttle pedal position and whether the brakes were on or off, he said.

Investigators determined that at about 2:30 p.m., as Torgerson was heading to catch the 3 p.m. ferry to Monhegan Island, she stopped her sedan on a downgrade to the wharf and behind an SUV, whose driver was talking to a parking attendant.

“During the first several seconds, the brakes were on and the throttle pedal was partly depressed, 33 percent or less,” Rushlau reported. “Approximately four seconds before the airbag deployment, the brake pedal indication changed from on to off, and the throttle pedal position changed to 100 percent. The brake pedal stayed off after that point, and the throttle remained at 100 percent for all but one second of the remaining time recorded.”

The sedan at first moved 4-5 mph as the sedan struck the rear of the SUV and spun it around. The speed then increased dramatically with the module recording it in one-second intervals — 4, 5, 10, 13, 22 and finally 31 mph when the airbag deployed, presumably when the sedan struck the terminal building, according to Rushlau.

After the car hit the building, it continued on and struck Coggeshall and a series of vehicles parked on the wharf. The sedan’s speed dropped to 17 mph immediately after the impact that caused the airbag to deploy. But then it increased again over the next three to four seconds to 32 mph.

The Golds were struck during this second stage of acceleration, according to Rushlau.

A blood test showed that Torgerson had no alcohol in her system, and officers saw no signs of illness or that the driver was under the influence of any substances at the time, the district attorney said.

Torgerson told investigators that the car suddenly accelerated as if the pedal was stuck to the floor or jammed. Her recollection after the sudden acceleration was a blur, she told officers.

Rushlau reported Thursday that Maine State Police accident reconstructionist Christopher Rogers examined the sedan and found no mechanical problems.

“I do not have a conclusive reason as to why Cheryl Torgerson accelerated her vehicle onto the Monhegan Boat Lines pier,” Rogers wrote.

In his four-page statement, Rushlau noted that operating a vehicle so as to cause death can be prosecuted as the crime of manslaughter, and operating a vehicle so as to cause serious bodily injury can be prosecuted as the crime of aggravated driving to endanger.

“Each of these crimes requires the state to prove beyond a reasonable doubt that the driver acted with at least criminal negligence,” he said, adding that “evidence available at this time is not sufficient to prove that Cheryl Torgerson acted with criminal negligence.”

Rushlau shared his decision with Coggeshall and Allison and Howard Gold last Friday.